[PATCH] mac80211: remove PRISM2_PARAM_DROP_UNENCRYPTED ioctl

Interestingly, wpa_supplicant doesn't use it, but uses the
currently unsupported IW_AUTH_DROP_UNENCRYPTED. So I guess
it doesn't matter anyway.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: Jiri Benc <jbenc@suse.cz>
Signed-off-by: John W. Linville <linville@tuxdriver.com>